Staphylococcus aureus blood stream infections in Cambodian adults

Abstract

Background: Staphylococcus aureus is a common cause of blood stream infection (BSI); treatment options are jeopardized by quickly emerging resistance. Epidemiological and resistance data on invasive S. aureus infections in Cambodia are scarce. Methods: Isolates and epidemiological data were recovered from patients with BSI presenting at Sihanouk Hospital Centre of HOPE between July 2007 and December 2010. Identification of S. aureus isolateswas performed by conventionalmethods. Antibiotic susceptibilities were assessed using disk diffusion andMicroScan (Siemens Healthcare) according to CLSI guidelines.Molecular characterization included spa typing, Staphylococcal Chromosomal Cassette (SCC) mec typing, Multi Locus Sequence Typing (MLST) and screening for presence of PantonValentin Leukocidin (PVL) and toxic shock syndrome toxin (TSST) encoding genes by PCR. Results: We observed 51 S.aureus blood stream infections in 46 patients (65.2% male, mean age 42 years (range 16-67 y), representing 12.0% of all clinically significant blood stream isolates. Comorbidity included diabetes (11.0%) and HIV-infection (23.9%); 7.8% of the S. aureus BSI were hospital-associated. In 21(41.2%) episodes, skin and soft tissue infections (SSTI) were the presumed focus of infection with 8 (38.1%) PVL-associated. Twelve isolates (23.5%) were methicillin resistant (MRSA); 5 of those were from HIV+ patients. Resistance rates for clindamycin, sulfamethoxazole-trimethoprim (SMX-TMP), fluoroquinolones and azithromycin were high, especially among MRSA (Table 1). FiveMRSA isolates displayed combined resistance to clindamycin, SMX-TMP, tetracyclin, erythromycin and moxifloxacin. No resistance for vancomycin was noted. The spa typing revealed 4 different types amongMRSA and 21 in MSSA. Predominant types were t189-ST188 (n=10; 6 were MRSA SCCmec IV), t1379-ST834 (n=4; all MRSA SCCmec IV and TSSTpositive), t159-ST121 (n=9; 8/9 PVL-positive) and t034-ST1232 (n=6; all MSSA and PVL-positive). Five patients had one or more